<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>P99 5.4.1 String对象</title>
</head>

<body>
    <script>
        var str = 'HelloWord';
        str.length;
        str.charAt(5);
        str.indexOf('o');
        str.lastIndexOf('o');
        str.substring(5);
        str.substring(5, 7);
        str.substr(5);
        str.substr(5, 2);
        str.toLowerCase();
        str.toUpperCase();
        str.split('1');
        str.split('1', 3);
        str.replace('World', 'JavaScript');
    </script>
</body>

</html>